Process of making insoles



Nov. 28, 1939.

H. G. LUMBARD PROCESS OF MAKING INSOLES Filed Sept. 12, 1939 n a .v M w I Patented Nov. 28, 1939 UNITED STATES PATENT OFFICE 3 Claims.

The principal object of the invention is to provide an insole having an unusually high degree of flexibility throughout its whole area or in any selected portion such, for example, as the forepart. Flexibility is of paramount importance especially in women's shoes and a great many various expedients have been adopted with this end in view. One of the limiting conditions of flexibility is that a shoe having a thin sole is uncomfortable because uneven objects underfoot can be felt by the wearer. Accordingly the present invention contemplates an insole which, while being extraordinarily flexible, is also'sufflciently thick and resilient to be comfortable under all conditions of wear.

Another object of the invention is to provide a flexible insole which may be used advantageously in shoes having an outsole attached by cement since shoes made in this manner tend otherwise to objectionable stiffness.

I have discovered that a particularly flexible insole may be produced by slitting or otherwise perforating it with a series of rows of transverse slits extending from edge to edge of the insole, intersecting both edges of the insole at spaced points and providing freely movable internal edges in the insole. This treatment not only produces an extraordinarily flexible insole, but it simultaneously expands or increases the area of the insole thereby introducing an important economy in the manufacture of insoles. For example, it permits the manufacturer to cut his insoles at least a half size shorter than required in the finished shoe and to gain a half size in the slitting or perforating operation. Preferably the insole is treatedby forcing bevellededge o knives or other cutting instruments of substantial "thickness into it forming lines or rows of slits separated by short bridges of solid material, and

I in this operation these bridges are stretched longltudinally and the slits opened at least to an extent that permits their opposite edges to move freely when the shoe is flexed in wear.

These and other characteristics of my novel process will be best-understoodrand appreciated from the following detailed description of Preferred ways in which it may be practiced as illustrated in the accompanying drawing in which,

Fig. 1 is a view in perspective showing an insole died out from sheet material,

Fig.. 2 is a view in elevation of one form of rotary slitting mechanism suitable for use in producing the insole material shown in Fig. 1,

Fig. 3 is a plan view illustrating an insole of somewhat different design from that shown in Fig. 1, and 5 Fig. 4 is a fragmentary view in perspective illustrating the slitting operation as it may be carried out upon an insole blank.

As illustrated in Fig. 1 the insole I4 is shown as produced from a composite sheet of material wherein the upper layer or ply is composed of three contiguous bands or strips II), II and i2 of material such as artificial leather or fibre board and this upper ply is united in continuous face to face contact with a layer l3 of resilient material such as ground cork and rubber composition or sponge rubber. In the upper ply the bands I0 and I2 which are cut into the toe, shank and heel seat portions of the insole may be relatively stiff, whereas the band H which is to be 20 out in the ball portion of the insole may be of a more flexible nature. Such insole material is available as a commercial product upon the market and is desirable from my standpoint although by no means necessary, since a homogeneous sheet may be employed for the upper ply of composite material.

As herein shown the central strip I I is slashed in a very special manner either before or after it is incorporated with the bands It! and I2 in the upper ply, but in any case before the upper ply is cemented to the lower resilient ply l3.

The slashes comprising the transverse rows of slits, cuts or perforations which extend entirely through the strip H are arranged in staggered relation, each being distinct and separated from the next by a short bridge of solid-material. The slitting may be effected by any suitable mechanism or tool. One such mechanism is suggested in Fig. 2 where is shown a pair of cooperating rollers 2| and 22. The roller 22 is provided with rows of segmental circumferentially arranged knives 25 of substantial thickness and is Uositively driven by a gear shown on the end of its shaft or by any other suitable means. A work table 20 is provided for directing sheet material insole blank from the'ply lli--Ill2 and then uniting it to a correspondingly died out resilient ply, but better economy is secured by following the procedure suggested in Fig. 1 of forming the complete composite sheet before dieing out the insole.

In Fig. 3 I have shown anotherdnsole con structed in accordance with the process of my invention. In this figure a. leather insole blank i is first rounded to the shape shown, that is to say, the blank is of nearly normal outline, its original length being indicated by. the dotted linell at the toe. Generally speaking, the blank which is provided is-somewliat shorter than and of-substantially the same width as the insole .desired. The ball part of the blank is vthen slashed or perforated with, a plurality of curved slits l6. Theseslits are arranged in rows extending transversely from side to side of the insole and intersecting both edges thereof in a plurality of spaced points. The slits or perforations may be made by any properly shaped tool having a bevelled-cutting edge such that the material of the insole is stretched and expanded as the re-v suit-of the slitting operation. The slits may be.

formed row by row beginning at the. ball line of the sole and working toward the toe, or they may be formed by a gang of cutters traveling trans:

versely across'the sole as would be the case in using the mechanism of Fig. 2, but in any case.

the forepart of the insole is simultaneously increased in length and rendered extremely flexible as the result of the slashing treatment described. It should be noted that it is important to intersect the edges of the insole so that no solid marginal frame shall be left in it. Such a solid portion would prevent the smooth ex.-

pansion of the insole and would cause buckling in adjacent slitted areas. t

The slitting step is further exemplified in Fig. 4 where a portion of an insole blank I8. is shown as being, slitted by a bevelled edge knife I9. As shown the knife passes completely throughthe material of the insole and at each step longitudinall'y stretches the adjacent inso le material.

.The collective result of these slits, asalready explained, is to enlarge and .render flexible the treated area.

and results in an exceptionally flexible and comfortable shoe bottom. It is not only extremely flexible, but it does .not' buckle or blister when the shoe is flexed, but lies in a fiat curve beneath the foot.

With its great flexibility however, the insole has sufficient body to protect the foot against uneven objects particularly when it is associated with a resilient cushion ply as suggested in Fig. 1.

In Fig. 1 an insole is shown in which the slashed and elongated body is cemented without An insole constructed as above outlined may be employed very advantageously, in the construction of women's shoes of all type,

initial tension to a resilient cushion layer I 3., It

is contemplated, however, that in many instances it may be advantageous to cut the leather insole blank short, out another ply into a full length blank, slash all or a portion of the leather blank in rows of distinct cuts which in some locations intersect the edges of the blank, elongate the slashed blank by tension to the length of the solid ply and then cement the two together with the slashed blank under tension and the toe .lin'es coinciding.

It will be apparent that the exact shape of the slits or slashes is of secondary importance so long as they pass entirely through the material and are of such a character as to, permit ex-.

pansion of the treated insole area and free the I opposedinternal edges for relative movement.

I have shown straight slits in the insole of Fig. 1 and curved slits in the insole of Fig. 3 and contemplate that the length, shape and character of the slits, slots or perforations may be varied in accordance with the requirements of the particular work. in. hand. For example, distinct groups of, small perforations arranged tran s'+ versely and intersecting the edge of the insole. at. spaced points wouldflbe satisfactory and within the scope of the present invention'. In all cases however the 'resultinginsole when stitched or'f; cemented to an outsole will lie fiat without buckling or blistering when the shoe bottom flexed and will not oppose the flexing of the outsole,'

but will follow it without resistance.

The insole herein shown as produced by niy'" novel process may be employed in tensioned QQnE-i dition in the' finished shoeas described and claimed in my copending application, Ser. No.

249,987,, or it may be tensioned in a self-com tained insole, or it may be employed without j v H being subjected to any substantial initial tension on the last or otherwise. Moreover, while I have referred specifically to insoles as embodying my invention I use the term to include also soles known technically as middle soles.

Having thus disclosed my invention and described in detail several exemplary ways of practicing it, I, claim as new and desire to'secure by- Letters Patent:

1. A process of making flexible insoles, which comprises providing an insole blank of nearly normal outline, elongating the insole blank by' slashing it from edge to edge with rows of spaced;

through and through slashes, each. slashbeing formed by a'cuttlng instrument of substantial thickness having a beveled edge.

2. A process of making flexible insoles, which comprises providing an insole blank of nearly normal outline, and elongating the insole blank by slashing it from edge to edge with rows of spaced through and through curved slashes, each curved slash being formed by a cutting instrument of substantial thickness having a beveled.

edge.

to' the desired length by slashing it from edge to edge with rows of spaced, through'and through slashes, each slash being formed by a cutting instrument of substantial thickness having a beveled edge.

1 may a. LUMBARD.

3. A'process' of making flexible insoles, which comprises providing an insole blank which is shorter than and 01' substantially the same width as the insole desired, elongating the-insole blank. 

